(i) Technical Field
The present invention relates to a print data processing apparatus and a non-transitory computer readable medium.
(ii) Related Art
In order to deal with an environment in which a toner or ink of a spot color is not available, a spot color is simulated by using a combination of basic colors. One of the issues that may be presented in this simulation concerns processing for an overlapping portion of a spot color object and another spot color object. For example, there may be a case in which the color of an overlapping portion of objects having the same spot color turns out to be different from that obtained when printing is performed by using spot color plates. This issue will be discussed later.
Print data described in a page description language (PDL) is converted into an intermediate data format, and then, data in the intermediate data format is rasterized (converted into a raster format) and printed. In this printing technique, the above-described simulation of a spot color by using basic colors may be performed when PDL data is converted into intermediate data. In this case, an object expressed by a spot color in PDL data is converted into an object group expressed by basic colors (including information concerning a transmission ratio) in intermediate data. The transmission ratio is a ratio at which the color of another object group superposed under this object is transmitted. The objects of the intermediate data are generated in accordance with the order of objects of the PDL data, and the generated objects are subjected to rasterizing processing in this generating order. Accordingly, it is now assumed that the following type of image in the PDL data format is input. A spot color object is superposed on a normal object constituted by only basic colors and another object of the same spot color is further superposed on the superposed object. In this case, this superposing order is also maintained in the intermediate data. Additionally, in the intermediate data, a spot color is represented by basic colors and a transmission ratio. Accordingly, in rasterizing processing for the intermediate data, the basic color components of the first spot color object in the superposing order are combined with an image obtained by rasterizing the normal object in accordance with the transmission ratio, and then, the basic color components of the second spot color object in the superposing order are combined with the resulting raster image (expressed by basic color components) in accordance with the transmission ratio. In this method, the color of an overlapping portion of the objects of the same spot color results in a color obtained by superposing the same spot color twice on the color of the normal object. In actual printing, however, the objects of the same spot color are integrated into one spot color plate, and the color of the overlapping portion of these objects results in, not a color obtained by superposing the same spot color twice, but the spot color itself.